A robot explorer sent through the Great Pyramid of Giza has begun to unveil some of the secrets behind the 4,500-year-old pharaonic mausoleum after it transmitted the first images behind one of its mysterious doors.

The images revealed hieroglyphs written in red paint that have not been seen by human eyes since the construction of the pyramid. The pictures also unveiled new details about two puzzling copper pins embedded in one of the so called "secret doors."

Published in the Annales du Service Des Antiquities de l'Egypte (ASAE), the images of markings and graffiti could unlock the secrets of the monument's puzzling architecture.

"We believe that if these hieroglyphs could be deciphered they could help Egyptologists work out why these mysterious shafts were built," said Rob Richardson, the engineer who designed the robot at the University of Leeds.

Built for the pharaoh Cheops, also known as Khufu, the Great Pyramid is the last remaining wonder of the ancient world.

The monument is the largest of a family of three pyramids on the Giza plateau, on the outskirts of Cairo, and has long been rumored to have hidden passageways leading to secret chambers.

Archaeologists have long puzzled over the purpose of four narrow shafts deep inside the pyramid since they were first discovered in 1872.

Two shafts, extend from the upper, or "Kings Chamber" exit into open air. But the lower two, one on the south side and one on the north side in the so-called "Queen's Chamber" disappear within the structures, deepening the pyramid mystery.

Widely believed to be ritual passageways for the dead pharaoh's soul to reach the afterlife, these 8-inch-square shafts remained unexplored until 1993, when German engineer Rudolf Gantenbrink sent a robot through the southern shaft.

After a steady climb of 213 feet from the heart of the pyramid, the robot came to a stop in front of a mysterious limestone slab adorned with two copper pins.

Nine years later, Hawass explored the southern shaft on live television. As the world held its breath, a tomb-raiding robot pushed a camera through a hole drilled in the copper pinned door — only to reveal what appeared to be another door.

The following day, Hawass sent the robot through the northern shaft.

After crawling for 213 feet and navigating several sharp bends, the robot came to an abrupt halt in front of another limestone slab.

As with the Gantenbrink door, the stone was adorned with two copper pins.

"I dedicated my whole life to study the secrets of the Great Pyramid. My goal is to finally find out what’s behind these secret doors," Zahi Hawass, Egypt's Minister of State for Antiquities Affairs, told Discovery News in a recent interview.

In the attempt to solve the mystery, Hawass established the Djedi project, a joint international-Egyptian mission, which he named after the magician who Khufu consulted when planning the layout of this pyramid.

"I selected the Djedi team during a competition that I coordinated to pick the best possible robot to explore the shafts in the Great Pyramid," Hawass said.

The winning robot, designed by Leeds University, has indeed gone farther than anyone has ever been before in the pyramid.

The project began with the exploration of the southern shaft, which ends at the so called "Gantenbrink’s door."

The robot was able to climb inside the walls of the shaft while carrying a "micro snake" camera that can see around corners.

Unlike previous expeditions, in which camera images were only taken looking straight ahead, the bendy camera was small enough to fit through a small hole in a stone "door," giving researchers a clear view into the chamber beyond. It was at that time that the camera sent back images of 4,500-year-old markings.

"There are many unanswered questions that these images raise," Richardson told Discovery News. "Why is there writing in this space? What does the writing say? There appears to be a masonry cutting mark next to the figures: why was it not cut along this line?" Roberston wondered.

The researchers also were able to scrutinize the two famous copper pins embedded in the door to the chamber that had been glimpsed only from the front before.

"The back of the pins curve back on themselves. Why? What was the purpose of these pins? The loops seem too small to serve a mechanical purpose," Richardson said.

The new information dismisses the hypothesis that the copper pins were handles, and might point to an ornamental purpose.

"Also, the back of the door is polished so it must have been important. It doesn't look like it was a rough piece of stone used to stop debris getting into the shaft," project mission manager Shaun Whitehead, of the exploration company Scoutek UK, said.

The Djedi robot is expected to reveal much more in the next months.

The device is equipped with a unique range of tools which include a miniature "beetle" robot that can fit through a 19 mm diameter hole, a coring drill, and a miniaturized ultrasonic device that can tap on walls and listen to the response to help determine the thickness of the stone.

The next step will be an investigation of the chamber's far wall to check whether it is another door, as suggested in the 2002 live exploration, or a solid block of stone.

"Then we are going to explore the northern shaft," Richardson said.

The team has committed to completing the work by the end of 2011. A detailed report on the findings is expected to be published in early 2012.